By using a short-range communication such as Bluetooth (registered trademark) or the like, in cooperation between a mobile phone carried in a car and an in-vehicle information terminal, a hands-free call can be achieved. Further, it is well known that the in-vehicle information terminal has a function of acquiring a telephone number of an opposite party and a communication state (during talk, hold, or the like) from the mobile phone and displaying these information on a screen of the in-vehicle information terminal.
As information acquisition by the in-vehicle information terminal, for example, the mobile phone voluntarily notifies predetermined information. Further, the in-vehicle information terminal issues a command that requests transmission of information, and the mobile phone transmits the requested information in response to the command.